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A090155 Primes of the form identical digits preceded by a 7. 3
7, 71, 73, 79, 733, 7333, 79999, 733333, 799999, 71111111, 799999999, 79999999999, 79999999999999999999999999, 79999999999999999999999999999999999999999999999999 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..24

MATHEMATICA

Select[ FromDigits /@ Flatten[ Table[ PadRight[{7}, i, # ] & /@ {1, 2, 3, 4, 5, 6, 7, 8, 9}, {i, 2, 50}], 1], PrimeQ[ # ] &]

CROSSREFS

Sequence in context: A200929 A111462 A045713 * A326740 A107163 A179784

Adjacent sequences:  A090152 A090153 A090154 * A090156 A090157 A090158

KEYWORD

nonn,base

AUTHOR

Robert G. Wilson v, Nov 22 2003

STATUS

approved

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Last modified December 8 12:28 EST 2021. Contains 349596 sequences. (Running on oeis4.)